


Stiles, the Kink Enabler

by halcyon1993



Series: The Kinky Adventures of a Wolf and His Boy [56]
Category: Teen Wolf (TV)
Genre: Aftercare, Alpha Derek Hale, Anal Fingering, Anal Sex, Barebacking, Biting, Bottom Stiles Stilinski, Breeding, Childbirth, Derek Hale Needs To Use His Words, Dirty Talk, Established Relationship, Face-Fucking, Fluff and Smut, Hairy Derek Hale, Happy Ending, Knotting, M/M, Mates Derek Hale/Stiles Stilinski, Mating Cycles/In Heat, Mpreg, Oral Sex, Plot What Plot/Porn Without Plot, Possessive Derek Hale, Post-Coital Cuddling, Potions, Pregnant Stiles Stilinski, Rimming, Rough Sex, Self-Lubrication, Tooth-Rotting Fluff, Top Derek Hale
Language: English
Status: Completed
Published: 2018-11-21
Updated: 2019-02-10
Packaged: 2019-08-27 06:36:02
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 3
Words: 12,826
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/16697299
Author URL: https://archiveofourown.org/users/halcyon1993/pseuds/halcyon1993
Summary: Stiles begins to suspect that Derek has a breeding kink.





	1. Chapter 1

**Author's Note:**

  * For [sisforsterek](https://archiveofourown.org/users/sisforsterek/gifts).



> As always with this series, don't judge me for the depravity I have written…

It's Scott and Allison who plant the first seed. No pun intended.

It's the summer after college graduation when the couple ask everyone to gather together for a meeting at the rebuilt Hale house in the preserve. Stiles and Derek have been living there together for three years now, after Stiles spent a single year living in a dorm room to appease his dad. The rest of the pack is present as well, spread out across the three sofas in the huge living room. Derek and Stiles, as the alpha and alpha's mate, are side by side on the main sofa, while Scott and Allison stand in front of the fireplace, his arm around her shoulders. Both wear ridiculously beatific smiles.

"Well?" Erica prompts impatiently when neither of them speak. "We're waiting."

Scott's smile turns bashful before returning to its previous sunny state. "We have some news," he says excitedly. He looks to Allison, allowing her to reveal their surprise.

"I'm pregnant!" she exclaims, putting a hand on her flat stomach.

What follows are several minutes of chaos as the pack celebrates. Erica's impatience vanishes and is replaced by unadulterated excitement. Jackson actually congratulates Scott and Allison and seems to mean it, a far cry from the cantankerous asshole behaviour he perfected in high school. Not even Derek is immune to the convivial atmosphere, his lips curled into a proud smile. As for Stiles, he hugs his best friend tightly, pats him on the back and tells him that he's going to make an amazing dad.

When things calm down again, the questioning begins. It's mainly the other girls who carry it out, wanting to know when the due date is, if Scott and Allison were trying or if the pregnancy was just a happy accident, if they have any names picked out yet. Stiles doesn't really participate, just sits back with Derek and basks in the joy of the moment. It isn't until he looks at his mate and sees the funny way Derek is staring back at him that he thinks something might be up.

"You okay?" Stiles asks him, concerned.

Derek doesn't respond at first, just keeps his gaze glued wistfully to Stiles' lower torso. He only stops when Stiles waves a hand in front of his face. "Sorry, what?" he says.

"I asked if you're feeling okay. You seem kinda out of it."

"Oh, right. Don't worry; I'm fine."

"If you're sure."

"I am."

Stiles doesn't entirely believe it and can't figure out why Derek was feeling wistful, but he lets it go with a simple, "Alright."

* * *

Six months later, the seed finally starts to grow when Scott stops by the Hale house again. Derek is out on a run, and Stiles is in the kitchen when his friend arrives, so he doesn't see that Scott looks different right away. He hears the beta groaning softly behind him and turns around to find out what's wrong—he knows that groan, and it usually doesn't bode well. When he actually sees Scott, his eyes widen.

"What the hell is that?" Stiles enquires, pointing to the prominent bump beneath Scott's shirt.

"An empathy belly," Scott says sadly.

"And that would be…?"

Scott lifts his shirt so that Stiles can see. "It's supposed to help men understand what pregnancy's like for women."

Stiles pokes the belly and winces at how solid it seems. "Does it work?"

"It fucking sucks!" his friend replies. "Lugging around an extra thirty pounds like this…I'm telling you, my back has never hurt so bad. Not even that time Jackson tackled me too hard before I got bitten and I ended up being put on bedrest for a week hurt this bad."

"Huh."

"That's it? Huh? That's all the sympathy I get?"

"Well, I know you must've done something to deserve this, so…"

"Hey!"

"Well, did you?"

Scott looks offended for all of two seconds before he hangs his head and murmurs, "Yeah."

Stiles laughs. "Let's hear it, then."

"Allison was complaining about how her legs were sore and how she had to pee every five minutes, and I made the mistake of saying she must be exaggerating a bit."

"You didn't."

"Yup."

Stiles shakes his head. "Oh, Scott, you idiot."

"Anyway, this stupid belly is my punishment. She'll only let me take it off to shower, and I have to keep it on until she gives birth. And there are _heavier_ versions, dude."

"Guess you're just gonna have to watch what you say from now on," Stiles says, turning back to the potatoes.

Scott groans again.

* * *

When Stiles finishes with the potatoes, he goes to the fridge to get the chicken breasts he swears he remembers seeing on the bottom shelf that morning. But there's no meat in sight.

He sighs. "Damn it."

"What's up?" Scott asks from his stool at the kitchen island.

"We don't have chicken. Derek really wants some tonight. I'm gonna have to run to the store real quick."

"I could go for you," Scott offers.

"Would you?"

"Yeah, sure. If…if you don't tell Allison that I won't be wearing the empathy belly when I go."

Stiles glances at his friend to find him taking off said belly. He leaves it on the island and is out of the kitchen before Stiles can even agree to anything.

"What kind of chicken?" Scott calls from the foyer.

"Breasts! Four, please!" Stiles shouts back.

"Got it!"

After the front door opens and closes, Stiles guesses he should resume preparing the rest of his and Derek's dinner that evening, but he doesn't. At least not right away. Instead, his eyes fall on the empathy belly Scott left behind. He can't help but be curious. Scott made it sound absolutely horrible, and Stiles has heard many tales of how wonderful and awful a real pregnancy can be. As a man, it's nearly impossible for him to actually experience what it's like, not without some magical intervention. He has done enough research into magic since discovering his spark that he knows there's a spell out there for that, but he has never considered using it on himself. So the empathy belly will have to do…at least for now.

Mind made up, Stiles grabs the contraption, lifts up his T-shirt and straps it on.

"Damn, Scott wasn't kidding," he grumbles once it's on. "This thing weighs a tonne."

With a shrug, he pulls his T-shirt back down and heads out into the foyer to look at his reflection in the mirror on the wall there. He turns sideways and rubs his hand over the swell of the fake belly and is struck both by how odd it is and how…intriguing. Part of him gets stuck on what it would be like were the belly real, were there really a kid growing inside of him.

Derek's kid.

"Dangerous thoughts, Stiles. Dangerous thoughts," he tells himself.

Suddenly, the front door opens again, startling Stiles out of his imagination. He spins around, expecting it to be Scott—it would be just like him to forget something—but it's actually Derek getting back from his run, his grey tank top stained with sweat. The alpha stares right back at Stiles with a dumbfounded look on his pretty face. After a moment, his expression changes into that longing one Stiles remembers seeing the day Allison announced she was pregnant. It's even more pronounced this time, and it doesn't take a genius to figure out why.

"W-what are you doing?" Derek asks him, his voice choked.

"Uhh…it's Scott's fault."

"How?"

Stiles explains about Allison making his best friend wear the empathy belly. "I just thought I'd see what all the fuss was about."

"Oh." Derek finally seems to regain control of himself. His countenance becomes impassive.

"Yeah. It's actually kinda cool. Heavy, but cool."

Derek says nothing.

Getting a mischievous idea, Stiles reaches out and grabs Derek's hand. He brings it to the belly. "Here, touch it. Pretty cool, right?"

Derek is frozen in the doorway for a few seconds, staring at his hand on the empathy belly, but then he rubs it a bit and…yup, there's that look again.

Interesting.

"If you think it's cool, then sure," Derek says, dropping his hand. He resolutely keeps his eyes away from the belly as he breezes past Stiles. "I'm gonna shower."

Stiles watches him ascend the stairs with a smirk. This is going to be fun.

* * *

That night, long after Scott got back with the chicken and left again with the empathy belly, Stiles finishes washing up in his and Derek's en suite bathroom and walks back out into the bedroom. Derek is already in bed, sitting up against the headboard with the sheets pulled over his lap, a book in his hand and his gloriously hairy chest on display. Stiles climbs in next to him and sees when he pulls back the sheets than the werewolf is only wearing a pair of tight, black boxer-briefs that leave almost nothing to the imagination.

Perfect.

To get his mate's attention, Stiles insinuates himself beneath Derek's chin and starts kissing down the side of his neck.

"You're in the mood tonight, I take it?" Derek observes, shutting his book.

Stiles smirks into the alpha's warm skin. "Always. You wanna…?"

"I could be convinced."

"Like you can ever resist my charms. I'm too irresistible."

"And cocky."

"Got it from you."

Stiles can almost hear Derek's ensuing eye roll and nips him gently with his teeth. The mark heals almost instantaneously.

"Alright, fine," Derek assents, setting his book on his nightstand.

He throws the sheets to the foot of the bed, pushes Stiles over so that he's lying on his back and then positions himself between Stiles' legs. After a moment spent staring into each other's eyes, Derek leans down and captures the younger man's mouth in a passionate kiss that takes Stiles' breath away. His Sourwolf has always been an excellent kisser. Derek slips his tongue inside Stiles' mouth, making him shudder as goosebumps appear on his arms and his cock goes from interested to rock-hard in mere seconds within the confines of his Deadpool pyjama bottoms. He threads the fingers of his right hand through Derek's hair and rests his left on Derek's broad chest, his pinky finger ghosting over the werewolf's sensitive nipple.

"What d'you want?" Derek murmurs against Stiles' lips.

"Want it rough," Stiles says eagerly, pulling his mate's hair to get his point across.

"I think I can manage that."

In the next second, Derek pulls back, rips off the rest of their clothing, leaving them both naked, and then rises up on his knees, his nine-inch cock sticking out from the nest of dark curls at the base. The head is still partially hidden by his foreskin, a sight that never fails to make Stiles drool.

"Wanna taste you," he rasps, making grabby hands.

Derek smirks. "How bad?"

"Really fucking bad," Stiles tells him. "Please, just get up here and fuck my mouth already."

This must be just what Derek wanted to hear, because in the next second he straddles Stiles' sternum, wraps a hand around the base of his cock and smears the fat head over Stiles' lips, painting them with his pre-come. Stiles opens his mouth and attempts to suck him inside, but Derek teases him by moving his hips back so that his cock is just out of reach. He doesn't move again until Stiles rests his head back on the pillow.

Stiles pouts up at his mate. "You're mean."

"Tonight, I will be."

Stiles keeps up his disapproving act for another two seconds, and then he grins. "Good."

Derek relents, grabbing Stiles' hair and yanking him onto his cock. Stiles goes willingly, letting his Sourwolf do all the work as his mouth is invaded by several thick inches. Derek thrusts in and out a few times, letting Stiles get used to him, and then he pushes in deeper so that his cock head hits the back of Stiles' throat. He doesn't stop when his mate chokes on it, just gives it to him rough like he asked.

"God, you feel so fucking good!" Derek gasps. "So warm…"

He tips his head back and pinches one of his nipples with his free hand as he continues to fuck Stiles' face, gradually picking up the pace until his hairy balls smack into the underside of Stiles' chin. For Stiles' part, he places his hands on Derek's muscular thighs and holds on for the ride, his own erection not flagging one bit even as Derek keeps choking him on his cock and makes him cry.

Eventually, Derek must get tired of simply using Stiles' mouth. He pulls out, flips the human over onto his hands and knees and spreads his cheeks, giving himself a peek at Stiles' tight little asshole. "Beautiful…" he whispers, right before he shoves his face between Stiles' cheeks and eats him out like a starving man. Stiles hangs his head and pants as he is given the rimming of a lifetime, his hands fisted in the sheets so hard that he thinks he actually hears fabric tearing. He doesn't give a damn. It's simply not possible, not with his mate's talented tongue wiggling against his rim and the scrape of Derek's stubble against his sensitive crack.

"Yeah, get me wet!" he says. "Get me ready for your huge alpha cock!"

Derek works his tongue into Stiles' hole and laps at his inner walls, a thunderous growl emanating from his chest. Stiles feels the pinpricks of claws on the flesh of his ass and is pleased with himself for getting his Sourwolf to let go of his control. It isn't that often that Derek gives into his more animalistic side for fear of hurting Stiles, so whenever it happens, Stiles makes sure to savour it. He has a feeling that this evening will be the most wild night they've ever had.

At least, it will be if his plan continues to work.

Derek eats Stiles out for a while longer. Nearing the end, he slides a single finger in alongside his tongue and presses once against Stiles' prostate, making him cry out.

"There it is," he says, smugness clear in his voice.

"Derek, please…" Stiles begs, wanting to be filled more.

"So needy."

"For you," Stiles agrees, arching his back sensuously. "Want your cock."

Derek chuckles and smacks Stiles' right ass cheek once. "How can I say no when you ask for it so nicely?"

Stiles jolts forward on the bed and falls forward, his cheek pressed to the mattress. He stays up on his knees, though, the perfect angle for Derek to fuck.

The perfect show of submission.

Stiles thinks approvingly that he's like a bitch in heat with how much he wants Derek's cock inside of him, stretching him wide. He certainly feels wet enough, Derek's saliva practically dripping from his hole.

"Gonna give it to you," Derek promises darkly, plastering his front to Stiles' back. He takes Stiles' earlobe between his teeth and nibbles on it.

"Please…" Stiles whimpers piteously.

"Shh, I've got you, baby."

Stiles nearly sobs with relief when he finally feels Derek's cock where he needs it. His rim protests as the head stretches it, and then it pops past and Derek sheaths the rest of himself inside Stiles' body with one brutal snap of his hips. He sets a fast pace right away, barely giving Stiles time to adjust. Stiles doesn't really need it. He wasn't prepped enough for it not to burn, but he quite likes a bit of pain with his pleasure. Plus, it only adds to the fantasy he wants to create, taking it from behind like this by a big brute of an alpha who is going to impregnate him.

Stiles screams when Derek strikes his prostate dead-on. "Fuck!"

"You like that?" the alpha asks, already knowing the answer.

"Yes!"

"Tell me."

"Love it so much, Der! Your cock feels so good inside me. Fill me up with your come! Put your cubs in me! _Breed_ me!"

Derek falters then, surprised by Stiles' words. He doesn't stop fucking him, though.

"Y-you want that too, don't you?" Stiles asks him breathlessly, craning his neck to look Derek in the eye. He finds red staring back instead of hazel. "I saw your reaction to the empathy belly. You wanted it to be real. You want to actually put your kid in my belly."

Derek whines helplessly and hides his face in Stiles' neck. The tips of his ears turn an adorable pink, a contrast to the way he keeps pounding Stiles' ass.

"Yeah, you do. Do it, Der," Stiles urges. "Be a good alpha and breed your mate."

Derek makes that sexy growling sound again, wraps his arms around Stiles and squeezes him tight as he switches from long, powerful thrusts to short, filthy grinds of his hips. This makes his cock press nearly constantly against Stiles' prostate and sets off fireworks behind his eyelids.

It's no longer possible for Stiles to spew filth about Derek breeding him up, his breath catching in his throat, but he doesn't need to anymore. He got the message across, and just a few seconds later Derek bites his neck with blunt human teeth and his knot begins to swell. The sound Derek makes now is somehow both vulnerable and possessive as his cock twitches in the clutch of Stiles' ass, painting Stiles' insides with his creamy jizz.

Stiles moans and reaches for his own cock. The massive size of his mate's knot hitting all the right places like always, it takes just two strokes for him to achieve orgasm as well, and then his legs give out and he collapses fully onto the bed with 200 pounds of sweaty werewolf on top of him.

"That was amazing…" he says, blinking sluggishly.

Derek keeps his face hidden as he rolls them onto their sides. "You really…you really don't mind?"

"Mind what? The breeding thing?"

Derek nods slowly, his arms tightening as he keeps filling Stiles with his thick alpha seed, his orgasm prolonged by his knot.

"Nope. I actually kinda love it," Stiles reassures, placing a chaste kiss to Derek's temple.

"It's…it's an alpha thing, I think. The need to breed."

"You don't need to explain. It's honestly hot as fuck, and I'd be lying if I said seeing myself with that stupid empathy belly didn't give me ideas."

"…Really?"

Stiles tells Derek about the spell he'd found a while back that would enable him to carry an alpha's child. The desire practically radiates off of Derek, but he doesn't ask Stiles to do it for him. He leaves the choice entirely up to his mate, which only makes Stiles want to give it to him even more.

"What do you think?" he enquires, genuinely contemplating it now.

"You'd really want to carry my baby?" Derek counters. It's obvious he finds it too good to be true.

"Yup."

"But…how would we explain it to people?"

"Well, my dad and the pack would know, and they're the only ones who'd really need to know. Everyone else would just think I gained weight or something, and once our kid's here, we could just say we used a surrogate or something."

"You've put a lot of thought into this," Derek comments.

"Like you haven't."

"I guess so."

"So are we gonna do it?"

"You're one hundred percent sure you'd be okay with it?"

Stiles rolls his eyes fondly. "There's not a doubt in my mind."

"Then…okay."

Stiles cuddles further back into the alpha's embrace. "Good. We can go ask Deaton about it tomorrow."

Derek is silent for a few minutes, and then he kisses Stiles neck. "Thank you," he whispers.

God, Stiles loves him. "You're welcome, Sourwolf," he replies.


	2. Chapter 2

First thing the next morning, Stiles drives across town to have a talk with Deaton, leaving Derek still asleep in their bed. He arrives so early that there are only two vehicles in the parking lot—Deaton's and the receptionist's—which is perfect because Stiles wants to do this as soon as possible and with as little chance of having an unwelcome audience as there can be. This is going to be awkward enough as it is, but he knows it'll be worth it. He can't believe how much he wants to have Derek's kid. It's to the point where he'll be heartbroken if Deaton either says there is no such spell that will make it possible or he simply refuses to help.

After parking next to Deaton's car, Stiles climbs out of his Jeep and approaches the entrance to the clinic with sweaty palms.

 _Please work,_ he begs whichever deity is listening.

Entering the building, Stiles walks through the waiting room, pushes through the waist-high barrier that keeps out unwanted supernatural visitors and walks into the hallway beyond. Following the sounds he can hear, he finds Deaton rifling through the cupboards in the main examination room. The receptionist, a tiny woman with red hair cut close to her head, is with him.

"Mr. Stilinski, this is a surprise," the vet greets, turning around with a white box in his hand. Some medical jargon is printed on the side in dark-blue letters.

"Uh, yeah. Hi." Stiles waves pathetically.

Deaton smiles at him as he sets the box on the examination table bolted to the middle of the floor. "That'll be all for now, Karen. Thank you."

"Sure thing," the receptionist says. She eyes Stiles curiously on her way out.

Once the door is shut, Deaton addresses his visitor again. "What brings you by? No one's in danger, I hope."

"No, it's nothing like that."

"I'm glad to hear it. So, how can I help you today then?"

Stiles wipes his hands on his chinos and then shakes out his arms to rid himself of some of the nervous energy coursing through his veins. "I have a question," he begins hesitantly, "and it's probably gonna sound really weird."

"You definitely know how to pique someone's interest, don't you?" Deaton chuckles. "Alright, I'm listening."

"D'you know that empathy belly that Allison's making Scott wear?"

Another chuckle. "It's made an appearance around here a few times, yes."

"Well, Scott brought it by the house yesterday and I tried it on. Derek saw me wearing it and…his reaction gave me an idea. Now here's where it gets weird."

Deaton's amusement remains, the corners of his mouth turned up ever so slightly. "I think I can already guess, but just to make sure, I think you'd better tell me straight out."

The blood rushing to his face, Stiles clears his throat and avoids the vet's gaze as the words pour from his mouth like a waterfall. He definitely gives away too much, but there's not much he can do about it what he's this nervous.

"It was obvious that Derek liked it when I looked like I was pregnant, and I actually kinda liked it too, surprisingly. That lead to some kinky-as-hell sex last night where I played up the fantasy of Derek knocking me up for real and then we talked and I brought up that you might know a spell or something that would enable him to actually do that. So now I'm here, and I should really stop talking, so I'm going to. Right now." Stiles takes a shuddering breath to refill his oxygen-deprived lungs. "So, yeah, that's why I'm here," he concludes.

Deaton is full-on grinning now, much to Stiles' humiliation. "I was right," he says smugly, crossing his arms over his chest.

Stiles ignores him and shuffles his feet, the soles of his shoes scuffing the linoleum floor. "Is it possible?"

Holding a finger to his chin, the vet thinks for a moment before turning and walking over to a tall cabinet positioned in the corner of the room. He opens it and returns with a heavy-looking tome in his hands. "I think I have just the thing. It's rare, but believe it or not, you aren't the first person to ever wonder if it's possible. Luckily for you, it is, thanks to Derek being an alpha and you two being mated. It wouldn't be doable otherwise."

"Guess it's a good thing Derek killed Peter, then," Stiles says before he can think better of it. He smacks a hand over his mouth, muffling his next words. "Don't tell either of them I said that!"

"Your secret's safe with me."

Stiles lowers his hand again. "So how does it work? Is it a spell, a potion, what?"

"A potion." Deaton sets the book down carefully on the examination table and flips through the weathered pages until he finds what he wants. "Coincidentally, I just restocked my supplies, so I have everything needed to brew it here right now."

"That's convenient."

Deaton nods. "Does Derek know you're asking me this today?"

"Mmhmm. We agreed we'd come see you."

"But you came alone."

"Yeah…" Stiles rubs the back of his neck. "If it turned out the answer was no, I wanted to tell him in private so that he didn't have to put on a brave face, y'know?"

"I see."

"How soon can you make it?"

"One second," Deaton says. He walks back out into the waiting room, Stiles presumes to check with his receptionist about how many appointments he has today. He's back quickly. "Unless someone has an emergency late this afternoon, I'll be able to brew it then. You'll have it in your hands by this evening, if that's what you want."

"It is."

"I need to give you a word of warning, though."

"Oh?"

"This potion is going to change your…plumbing, for lack of a better term," Deaton explains, his countenance serious. "You'll retain your usual anatomy, but it'll give you a womb as well. This process will be incredibly painful. Think the worst stomach ache you've ever had and multiply that pain by a hundred. It won't be over quickly, either—from previous cases, it'll take around two hours. There's also the issue of giving birth."

"Ouch."

"Yes. You won't deliver via traditional methods because, while you'll have a womb, you _won't_ have a vagina. A C-section will be necessary when the time comes."

Stiles wrinkles his nose. "Don't suppose I can just schedule one with the hospital."

"As you'll be a pregnant man, definitely not," Deaton confirms. "But, luckily for you, you have two people with medical knowledge in your life who are already aware of the supernatural."

"You and Scott's mom?"

"Correct."

Stiles thinks back to the longing on Derek's face when the alpha saw his round belly. It strengthens his resolve. "Well, that settles it, then. But going back to the transformation, can't Derek just take some of the pain?" he asks. He doesn't particularly like the idea of Derek doing that because he never likes to know that his mate is hurting, but it will still be nice to have the option if it's too much for Stiles to handle on his own.

"No."

The younger man's eyes widen. "No?" he echoes.

"You'll have to experience it all yourself, otherwise the potion won't work."

"That's bullshit!"

"You want what is, for all intents and purposes, a miracle. To circumvent nature and do the impossible by getting pregnant as a man. That kind of thing requires…not a sacrifice, exactly. Think of it more like a test, an offering. Bearing the pain will prove you worthy."

Stiles sighs and resigns himself to his fate. It won't be pleasant, but he just knows that having Derek's kid will be worth it. "Alright. Guess I don't really have any choice."

"You do, though."

"By not doing this at all, I know. But Derek and I both really want this."

"There's always adoption," Deaton suggests. "Or surrogacy."

"No, I'm doing this," Stiles asserts, determination giving him strength. "I'll make it work."

"Very well." Deaton takes a moment to reread the page in front of him. "After it's done, you'll be able to become pregnant as many times as you want. The only stipulation is that any conception has to take place on the full moon."

"Because of the whole werewolf thing?"

"Exactly. Werewolves are tied to the moon, and when it's full, both it and Derek will be at their most powerful. You'll still be human, but your fertility will be in tune with the moon too. I can't say for sure, but I'd guess that, because of the nature of your future pregnancies, Derek's alpha status, and the fact that he was born a werewolf rather than being bitten by one later in life, it's highly likely that your offspring will turn out to be werewolves as well."

"Good to know." With the dangerous stuff Stiles used to get up to with Scott when they were children—like climbing trees and daring each other back and forth to see who could jump from the highest branch—he's glad that it'll be much harder for his and Derek's kids to injure themselves. God help them if their kids take after him in that way.

Deaton checks the time on his watch. "If nothing comes up, I'll stop by your house in the evening to drop off the finished potion. But for now, my first appointment is due to come in very soon, and there are still a couple things I need to do to prepare for it."

Stiles takes the hint. "I'll get out of your hair. Thanks for doing this."

"It's no trouble."

"See ya."

"Goodbye, Mr. Stilinski."

With that, Stiles exits the building, gets back in his Jeep and drives home again, ready to tell Derek everything Deaton told him.

* * *

That evening, Stiles sits on the edge of his and Derek's king-size bed in nothing but a pair of Deadpool boxer shorts. He looks down at the small glass vial in his hand, within which is a thick, orangey-yellow liquid; the potion that Deaton dropped off just half an hour ago. He can hear Derek spit toothpaste out in the sink and then the man himself comes back into the room, also dressed in very little. Ordinarily, the sight of his mate's gorgeous, muscular body would have Stiles raring to go, but he's too anxious right now for his dick to so much as twitch.

"I could smell your anxiety from the bathroom," Derek comments, coming to sit next to him.

"Well, I _am_ kinda scared," Stiles confides. "Deaton made it sound like it's gonna be like I'm being tortured or something."

Derek frowns and wraps his arm around the human's shoulders. "You can still back out. You don't have to put yourself through this for me."

"I'm not doing it just for you. I want you to knock me up too."

"And you're sure he said I can't take your pain?"

"Yup. No magic pain drain for me."

"Stiles…"

Sensing that Derek is having major second thoughts, Stiles pulls the stopper out of the vial and gulps the potion down in one go.

It tastes like pennies. "Ugh, that's disgusting!"

Derek's mouth is a thin line as he takes the empty vial and gets up to throw it in the dustbin like it personally offended him. "I wanted to talk a bit more before you did that," he chides gently.

"You were gonna try and talk me out of it," Stiles defends himself.

"I was. You don't like it when I'm in pain, and _I_ don't like it when _you're_ in pain."

"This pain'll be a necessary evil, though." Stiles gestures for Derek to come back over to him and takes both of his hands when he does. "I want you to swear something to me."

Derek's expression is apprehensive. "What?"

"Even if I beg you to, don't take away _any_ of my pain. I mean it. _None_ of it."

The alpha looks away. "You can't ask me to do that."

"I just did. Swear to me, Sourwolf."

"I can't."

"Yes you can. Think of our future kids. Just picture them, because that's what I'll be doing. Think about having a little boy or girl calling you Dada, holding his or her arms out to be picked up. Think about what they'll look like—will they have your eyes? My hair? Your adorable bunny teeth?"

It's clearly against his will, but Derek's mouth relaxes into a smile as he imagines what Stiles is describing to him.

"To get that, we just have to get through tonight," Stiles says. "It's only two hours. I can do this."

"I know you can."

"Then let me." Stiles tugs on Derek's hands, drawing him to stand between his legs. "Please?"

The werewolf takes a deep breath and then nods slowly. "Okay. I won't intervene."

"Not even if I beg you to. Seriously, even if I'm screaming and crying, you won't do your pain drain thing. Deal?"

Derek hesitates but after a moment agrees to that too.

"Okay then," Stiles says. He releases his mate's hands and scoots backward on the bed so that he can lie down comfortably for however long he has until the potion takes effect. "Come lay with me?"

"You don't even need to ask that," Derek responds. He climbs over Stiles and wraps him up tight in his arms, chin resting atop Stiles' head.

Another few minutes pass uneventfully, and then Stiles thinks he feels it. His stomach lurches, almost like he's about to throw up, but he knows that's not what's happening. Sure enough, another minute later, he inhales sharply when a bright pain hits him, emanating from his lower abdomen. He turns toward Derek and presses his face to Derek's hairy chest as he experiences what he would say is something akin to being stabbed. It's not much longer until the pain makes him basically insensible, and time no longer has any meaning.

* * *

When Stiles comes to, his skin is sticky with sweat and he doesn't remember ever being so tired. He groans, his throat raw.

"You back with me?" Derek asks, still holding him.

Stiles tries to speak but can't at first. He clears his throat and tries again, his voice more of a croak that anything. "Yeah."

"Never again," Derek tells him ardently, his arms tightening even further.

Stiles' first instinct is to apologise, but he wouldn't mean it. The past two hours were some of the worst of his life—Deaton wasn't kidding when he said it would hurt—but he doesn't regret doing it.

"Come on," Derek says, releasing Stiles and getting up. "We need to shower, I'll change the sheets, you're drinking an entire glass of water, and then you're going straight to sleep."

Stiles doesn't protest as his mate helps him to stand up as well and guides him into the bathroom. His legs are so wobbly that he would definitely collapse without the assistance, and he could definitely use a shower because, frankly, he stinks.

Derek leans him against the wall while he gets the shower going. "D'you feel any different?" he asks, holding his hand beneath the spray to gauge the temperature.

Stiles does a quick assessment of his body. "Not really. Just exhausted. I'm sure it worked, though. You didn't take any pain, right?"

The werewolf's response is a short, "No," as he kicks off his underwear.

"Thanks, Sourwolf."

"Sure."

Stiles easily picks up on his mate's agitation but says nothing about it until he has been helped into the spacious shower and Derek has begun washing him. "You're mad at me," he observes.

Derek's hands falter briefly as he soaps up Stiles' back. "A little," he answers. "Seeing you like that was just…it was incredibly distressing. The worst part was that I could do something about it, but I knew you didn't want me to, so I really couldn't."

Stiles looks back over his shoulder. "I'm not sorry I drank the potion, but for what it's worth, I _am_ sorry that I put you through that."

Derek's countenance remains unmoved for a few seconds, and then he thaws and resumes cleaning the sweat from Stiles' body. "Thanks," he murmurs.

"At least it's over now, and it was a one-and-done sort of thing."

Derek hums. "True."

"And when the moon's full next week, you can breed me for real." Stiles waggles his eyebrows.

This earns Stiles a proper smile again, and the tips of Derek's ears turn pink. "That'll be…"

"Hot as fuck? I know, right?"

Derek smacks Stiles' ass lightly and directs him to step beneath the shower spray to wash the soap suds down the drain. "I guess I admit I'm looking forward to it," he says quietly.

Stiles flicks his eyes down to Derek's crotch and snorts when he sees that he's half-hard. "I'd say you're doing a bit more than that. You can't wait."

Derek rolls his eyes but doesn't deny it.

* * *

The next few days are tough for Derek to get through. He meant what he said about the hours after Stiles drank the potion being an awful experience, but as time passes and he begins to feel the adrenaline in his veins from the full moon getting closer, his lingering annoyance at Stiles for drinking the potion before they could fully talk things out fades entirely.

He finds himself walking around nearly 24/7 with his dick refusing to go down all the way, and he steadfastly avoids being around any of his betas. He knows they'd be able to smell his arousal, and he really doesn't want to give them a reason to tease him—Erica, especially. She can get downright vicious.

When the night finally arrives, after Derek has finished checking in with all of his betas to make sure none of them are in any danger of losing control, he hangs up his phone and goes around the ground floor of the house, turning off all the lights and double-checking that the front door is locked tight.

Then he goes upstairs, where he can hear Stiles mumbling to himself in their bedroom.

"I think whatever that potion did is starting," the human says as soon as Derek has entered. He's shirtless and has his hand down the back of his jeans.

"What're you doing?" Derek enquires, bemused.

Glancing up, Stiles removes his hand from his jeans and holds it up, his fingers glistening. "Look."

Derek steps closer with a frown. "What about it? It's just lube."

Stiles shakes his head. "No, it's not."

"Then what is it?"

"I already told you—it's what the potion did to me," Stiles replies, squirming. "I'm…leaking."

Derek's response is to say, "What," so deadpan that it doesn't even sound like a question. He clears his throat. "You're _leaking_?"

"Uh-huh, and I'm feeling kinda hot," Stiles apprises. "Like, burning-up kinda hot."

Now that he mentions it, Derek notices the sweat beating on the human's brow and the pretty red flush that spreads down from his face to his neck and chest. Closing the rest of the distance between them, Derek puts his palm over Stiles' forehead to check his temperature and is alarmed when he actually feels the heat. As an alpha werewolf with a higher body temperature than Stiles, that shouldn't be the case.

"Didn't Deaton tell you about any of this? Warn you what would happen?" Derek questions.

"Beyond the pain of the transformation itself and giving birth? No." Stiles squirms again out of obvious discomfort. "But I have a theory about what's happening to me."

"Tell me."

"Well, y'know how actual female wolves go into heat when it's mating season?"

Derek goes still, his brain quick to follow Stiles' train of thought. "Yes," he says warily.

"Well…I think that's what the potion did to me," Stiles finishes, confirming Derek's suspicions. "I'm in heat, and I guess now it's time for my big, strong alpha to put some cubs in me."

Derek inhales sharply, and that's when he smells it, whatever substance is on Stiles' fingers. It's so sweet and alluring, and it gives credence to Stiles' theory. Derek's dick goes from its recently persistent state of half-hard to fully erect in no time at all, and before he can even think about it, his bestial side takes over, made stronger by the pull of the full moon. There's nothing Derek can do to fight it.

"Eep!" Stiles squeaks as Derek picks him up and throws him onto their bed. "What the hell?!"

"Get naked," Derek growls, morphing into his beta form. "Now!"

Stiles stares for a moment before he understands. "Oh!"

Derek is satisfied when, a second later, Stiles' jeans fly past him and he is blessed with the delectable sight of the younger man without any clothes. Derek swiftly follows suit, whipping his henley off over his head and ripping his own jeans open so violently that the button pops off and the zipper breaks. He doesn't give a shit, though; he can buy new jeans tomorrow. Right now, the only thing that matters is that he gets his dick inside of Stiles. Already the base throbs, his knot threatening to swell prematurely. He has to hurry.

Leaping onto the bed with Stiles, Derek roughly flips him over onto his front and yanks his hips up so that his ass is presented. "I see what you meant," he growls approvingly. His fangs get in the way of his tongue, slurring his words slightly. "You _are_ leaking."

"T-told you," Stiles says breathlessly, arching his back.

The human's asshole is soaked with a clear, slick substance that Derek still thinks looks like lube. It definitely doesn't smell like it, though, and after leaning down and licking all the way from Stiles' perineum, through his crack and to the top of his ass, he knows it doesn't taste like it, either. He doesn't have words to describe what it tastes like in his current state. All he knows is that it's delicious and he has to taste more of it.

He shoves his face between Stiles' pale cheeks and eats him out like he's lost in a desert and the viscous fluid practically pouring from Stiles' hole is his only source of hydration. His chest vibrates with a constant growl now, the sound of it filling the bedroom with his mate's loud moans.

"D-Derek!" Stiles gasps, his voice high-pitched and whiny.

"Feel good?" Derek asks right against Stiles' hole, his beard slathered with slick.

"Yes! God, and I thought rimming felt good before… Fucking hell, I'm so sensitive now."

Derek smirks and dives in again. He points his tongue, wiggles it inside and is surprised when it goes in with no trouble. Stiles' hole just opens right up for him.

"Derek, please…want you," the boy begs.

His own need a persistent ache between his thighs, Derek takes one last taste and then moves forward to blanket Stiles' back with his own body, his cock slotting between Stiles' wet cheeks. "You want this?" he asks, rocking his hips slowly back and forth.

"Yes! Please, give it to me!"

"Yeah? You want your mate's big cock inside you?"

Stiles whimpers and the side of his face smushes into the bedding when his arms give out. "Want your cock so bad…your knot…"

"You'll get it."

Derek reaches between them, grips his cock and aims the tip at Stiles' hole. Once he's in position, he pushes inside with one brutal thrust, filling his mate up with all nine thick inches at once. Stiles screams into the sheets, but Derek doesn't care. He pulls out immediately and starts up a fast pace, his hands gripping Stiles' hips so tightly that he knows he'll leave bruises behind. His claws prick pale skin, small droplets of blood beading up, but he doesn't care about that, either. The only thought that occupies his animalistic mind is how amazing Stiles' hole feels around his dick.

"Fuck yes!" Stiles cries, hands fisted in the sheets. He shoves his ass back onto Derek's cock with each thrust, obviously enjoying the rough mating.

"Mine!" Derek grunts, his heavy balls smacking Stiles' with each thrust.

"Yours!"

The way Stiles smells right now—like a fertile bitch in heat—does things to Derek that he didn't think were possible. It taps into the primal urges he has only recently allowed himself to feel and brings them roaring to the surface. As their mating goes on, Derek becomes the one to spout filth this time. He talks about what a good bitch Stiles is, and how Derek is going to breed him up good—knot him, fill him with come, and then make his belly swell as his alpha's cubs grow inside of his body. And, according to the bestial side of him, he's going to do it many, many times.

"Gonna keep you barefoot and pregnant for me," he grits out, leaning over Stiles again to say the words right into his bitch's ear. "Breed you again and again and again until the house is full of our cubs and everyone knows what a good bitch you are!"

"D-Derek!" Stiles gasps. He untangles one hand from the sheets and grabs Derek's hair to pull him into a messy kiss. It's full of teeth clacking, and Stiles' bottom lip ends up getting cut by one of Derek's fangs, but neither of them gives a damn. Derek actually likes it in his current state, and Stiles keeps kissing him with a real sense of desperation, like just having Derek inside of him isn't enough.

It's like he needs Derek to be _everywhere_ , to surround him entirely.

With Stiles' hole around his cock, Stiles' body writhing beneath him and the taste of his mate in his mouth, it doesn't take much longer for Derek's knot to swell. Popping it past Stiles' rim is more difficult with every thrust, Stiles making these sexy little choking sounds every time Derek does it, until Derek shoves it in one last time. He circles his hips in little grinding motions, working his knot in as deep as he can get it as it swells to its full size. He releases Stiles' hips just in time to stop himself from turning his skin to ribbons. When he orgasms, he shreds the sheets instead.

Stiles whines as Derek begins to spray his insides with thick come. His hole spasms around the alpha's cock, his own orgasm hitting him and making Derek's even more intense. He howls as pleasure washes over him, so much that he collapses atop Stiles, trapping his bitch beneath him.

It's his rightful place.

"Fuck…" Stiles says shakily, thoroughly worn out.

Derek still moves his hips as much as he can, still coming. He can't respond, so he tucks his nose into Stiles' neck and breathes in the delicious scent of him.

"That was amazing, Sourwolf," Stiles murmurs, clenching around Derek's knot. "It always feels good, but whatever that potion did dialled it up to 100. Hot damn…"

While they wait for Derek's knot to go down, both mates just lie there and enjoy the afterglow of their first proper mating. Derek pumps more than enough come inside Stiles to breed him several times over, so he's sure that it took.

When his knot is small enough, Derek picks himself up and pulls out of his mate's hole. He feels more in control of himself now, so he checks Stiles over to make sure that he didn't do too much damage. He feels bad when he sees the tiny wounds his claws left on Stiles' hips, but they'll heal quickly and Stiles hadn't complained in the heat of the moment. He finishes up his inspection by spreading apart his mate's cheeks to look at his hole, a sense of satisfaction causing him to grin when he sees how loose it is—sloppy too, come and more slick leaking out.

"Think it worked?" Stiles asks sleepily.

"I don't know," Derek answers. "How d'you feel? Still overheated?"

"Nuh-uh. Just tired."

"Hang on."

Getting off of the bed, Derek retrieves a damp washcloth from the bathroom and uses it to clean the worst of their mating from Stiles' body. Then he throws it across the room and climbs back onto the bed with the younger man, taking him in his arms.

"We should buy some pregnancy tests," Stiles mumbles, his breath blowing out over Derek's nipple.

"I'll stop by the pharmacy tomorrow."

"Cool. Sleepy time now…"

Derek chuckles when, not even a minute later, he hears Stiles snoring softly into his chest. He has to admit that their mating wore him out as well, so he closes his eyes and follows his mate into dreamland not too long after, the alpha in him content as can be with their hopefully pregnant mate in their arms.


	3. Chapter 3

For two weeks after the full moon, Stiles is in a constant state of anticipation. No matter where he is or what he's doing, part of his mind is back at home, on the two pregnancy tests that Derek had rushed out and bought the day after they hopefully conceived their first child. It was too soon to use them then, of course, so they've been hidden in the medicine cabinet above the sink, taunting both of them with the possibility of expanding their family.

Deaton is the only other person who knows what's going on, which has made for a lot of confusion from the rest of the pack. Stiles is even more fidgety than usual, much to Jackson's annoyance, and it's like Derek has reverted back to his old self, just grunting and growling at everyone.

When the morning Stiles and Derek have been waiting for dawns, both of them are out of bed early and in their en suite bathroom for the moment of truth. Derek gets the tests out of their boxes, rereads the instructions—out loud so that Stiles gets a refresher as well—and then there's nothing left to do but for Stiles to pee on the ends of the sticks.

"It's not the end of the world if they're negative," the human says, standing in front of the toilet. He's trying to convince himself as well as Derek.

Said alpha crosses his arms over his bare chest. "I know."

"We can just try again next month."

Derek sighs impatiently. "Stiles?"

"Yeah?"

"Would you just do it and put me out of my misery one way or another?"

"Oh! Yeah…" Stiles laughs a little hysterically. "Sorry, Sourwolf."

Taking a deep breath, he pulls his boxers down beneath his balls, takes hold of his soft dick and readies himself to empty his bladder. It takes a few seconds, the pressure of the situation giving him a small case of performance anxiety, but soon enough his dick twitches in his hand and he begins pissing. He quickly puts the appropriate end of the first test in the stream for a few seconds and then swaps with Derek to do the same with the second.

Derek places both tests on the edge of the sink, and when Stiles has finished and moved out of the way, he relieves himself too. Stiles hears the toilet flush while he grabs his phone from the bedroom so that they can time things, and then both mates sit side by side on the edge of the bathtub.

"God, this is excruciating!" Stiles whines, staring at the tests.

Derek puts his hand on the younger man's thigh and squeezes. "I know. I'm right there with you."

When it's finally time, the timer on Stiles' phone counted down, Derek gets up and holds his breath as he approaches the sink. Stiles stays where he is, feeling like he might throw up, his stomach churning unpleasantly. There's a tiny voice in the back of his head that says it's morning sickness, but he knows it's too soon for that. The queasiness is just because he's incredibly nervous. The way his hands shake almost violently is more proof of that.

"Well?" Stiles asks tremulously when Derek just stands there looking down at both tests, his back to him.

"They're…" the werewolf chokes, a reaction that could go either way.

"Would you just tell me already?! I'm dying here!"

Picking up the tests, Derek turns around with misty eyes and a shocked countenance. "You're pregnant," he announces, his shock turning into huge grin.

"I am?" Stiles leaps up and snatches the tests from his mate to check for himself, and sure enough, the positive readings are right there.

He quickly starts to tear up too, the tests blurring until they're unreadable, but it doesn't matter. He's already seen them. The tests clatter to the tiled floor as he drops them without thinking, freeing up both hands so that he can grab one of Derek's and press the other lightly to his flat stomach. He's a jumble of emotions, every single one of them good.

"We're gonna be dads," he warbles, sniffling.

"We are."

Derek puts his free hand over Stiles' on his stomach, both of them staring in awe. He takes a shuddering breath. "I can't believe this is really happening."

"Me neither." Stiles blinks to clear his eyes of tears. "I couldn't be happier, though."

Derek nods and presses his lips to Stiles' forehead.

Humming contentedly, Stiles leans into his mate and basks in the joy they share. "You know what we have to do now, right?"

"What?"

"Tell my dad and the others."

"Oh."

"Fun, right?"

Derek exhales a short breath of amusement through his nose. "If you say so."

"So how're we gonna break the news to them? I wanna tell my dad in private—he deserves his own moment to get excited about being a granddad—but I think we should tell the pack all at once."

"Whatever you want," Derek says quietly, thumb stroking back and forth over Stiles' belly.

"Whatever I want, huh?"

"I honestly think you could ask me for the stars right now and I'd find a way to get them for you."

Stiles chuckles. "That's very _Stardust_ of you. Does that make me Clare Danes? Because I'm definitely happy enough that I feel like I'm glowing right now."

Derek pulls back, and even though his eyebrows are furrowed, the smile remains on his lips. "What're you talking about?" he asks, confused.

Stiles rolls his eyes good-naturedly. "I swear you never get my pop culture references."

"You're gonna make me watch whatever movie or TV show that is, aren't you?"

"Hey, you did say I could ask you for anything," Stiles points out. He lifts his arms and rests them over Derek's shoulders, running his fingers through the short, dark hair on the back of his head. He grins again when Derek closes his eyes and makes a quiet nose of pleasure. "You have no one to blame for this but yourself, Sourwolf."

"Fine, fine…I'll watch it."

"Awesome. You'll like it. It was originally a book, but it's one of the rare cases where I actually prefer the movie."

"Now?"

Stiles shakes his head and bumps their foreheads together. He scratches his blunt nails over Derek's scalp just to make him shudder. "Nah, we'll watch it later. Right now, I'm on cloud 9 and am really in the mood to give my sexy mate some lovin'. Sound good to you?"

Derek opens his eyes again, revealing his blown pupils and the thin ring of red around them. "Sounds _very_ good."

"Then take me back to bed, Sourwolf. I don't plan on us leaving it again all day."

* * *

Stiles' dad is the first person the newly expecting parents tell. As far as the sheriff knows, it's just another one of his weekly dinners with his son and his pseudo son-in-law in his house, and Stiles is fine to let him keep thinking that until the lasagne he'd cooked and brought with him is all gone and there's no danger of choking. After all, it wouldn't be good if the sheriff was so shocked by the news that he choked to death on his food before he could meet his future grandkid.

Once dinner has been eaten and the trio have migrated into the living room, Stiles and Derek on the sofa and the sheriff in his armchair, Stiles catches Derek's gaze and silently asks, "You ready?"

Derek's response is a subtle nod.

"Dad, we have something important to tell you," Stiles says, looking toward the man. He links his fingers together with Derek's and rests their hands on his knee.

The sheriff lowers his beer from his lips and flicks his gaze down to Stiles' left hand. "I don't see a ring, so Derek can't have made an honest man out of you yet."

"No, we're not engaged," Stiles tells him. He pouts. "And who says he's the one who's gonna propose? I could be the one to propose to _him_ , thank you very much!"

Stiles' dad arches an eyebrow at him.

"Hey, I could!" Stiles insists.

"Sure, son."

"Oh just you wait," Stiles mutters, quiet enough for his dad not to hear. Derek still does, though, given the way he snorts.

"If you're not engaged, then what's going on?" the sheriff asks warily, tensing. "It's nothing bad, is it? No new creature in town threatening all of our lives?"

"No, it's nothing like that," Stiles answers hastily. "It's good news. _Really_ good."

His body relaxing, the sheriff sets his beer down on the coffee table and sits back in his armchair. "Well don't leave me hanging then, son."

Stiles glances at Derek and lasts another three seconds before his excitement bubbles over and it comes spilling out. "I'm pregnant!" he announces giddily. He doesn't miss how Derek puffs out his chest next to him, already acting like a proud Papa.

The sheriff blinks, dumbfounded. "Excuse me? You aren't…feeling sick, are you?"

Stiles smiles. "No, I'm not sick."

"Are you sure? No fever? The last time you had a fever, you talked all kinds of crazy stuff."

"I promise this isn't like that, John," Derek interjects. "It's real. Stiles is really pregnant."

"But…Stiles is male. I know. I was there when he was born."

Stiles giggles. "Oh trust me, Derek knows that too," he says, enjoying the growl he gets from said werewolf. He knows that Derek doesn't like him being open about their sex life, but he just can't resist sometimes. "Dad, you've known that werewolves, magic and all sorts of other supernatural stuff is real for years now. Is a pregnant man really that far out there after everything you've seen?"

"I…" The sheriff opens and closes his mouth several times. "I guess not. How did this happen?"

"Well, I went to Deaton last month…"

For the next few minutes, Stiles relays the conversation he'd had with the vet and talks about the potion he'd drank. He skims over the pain of the transformation and leaves out the more intimate details altogether because, as much as he loves to tease his mate and has almost no shame, even _he_ doesn't want to get into the details of the breeding itself with his dad.

The sheriff's eyebrows get progressively higher on his forehead as the tale goes on, until his eyes are about as wide as Stiles has ever seen them.

"You okay, dad?" Stiles asks when he has finished. "We didn't break you, did we?"

The older man looks away for a while, processing, and then he looks back at his son. "You're…you're really pregnant?"

"Yup. I took a couple tests earlier in the week. You're gonna be a granddad!"

The news truly sinks in then, and the next thing Stiles knows, his dad pulls him up from the sofa and embraces him so tightly that he might have bruised ribs afterward. He embraces his dad back anyway. Logically, he knew that the man would take it well and would be as happy with the pregnancy as he and Derek are, but he's still relieved. There was a tiny, _tiny_ part of him that was worried his son being knocked up might freak the sheriff out too much for him to enjoy the news of an impending grandkid, but it all turned out alright in the end.

When his dad pulls back and puts his hands on Stiles' shoulders, holding him at arm's length to get a proper look at him, he starts to tear up all over again when he sees that his dad is close to crying.

"Aww, c'mon, dad," Stiles chides softly. "You're gonna make _me_ cry again."

The sheriff just hugs him a second time. "Sorry, but I can't help it."

After a moment, he releases his son and moves on to Derek. The werewolf has always been very reluctant to let anyone touch him unless it's Stiles or Cora, but he doesn't protest as Stiles' dad pulls him into a hug of his own. He actually reciprocates, and Stiles thinks it's both because he's caught up in the jubilation the sheriff is feeling and because he doesn't want to disappoint the father of his mate. Stiles thinks back to when his dad accepted that his relationship with Derek was serious and that both of them were in it for the long haul. As well as giving Derek a mate, it gave him a reason to celebrate Father's Day again, something he hadn't had for over a decade at that point.

"God, this is the best news I've heard in years!" Stiles' dad says after Derek has extricated himself. "Have you told anyone else yet?"

"Nope," Stiles answers. "You were the first person I wanted to tell. We're doing the pack next. I kinda hope Scott faints."

"If he does, record it for me."

"Will do, Pops."

"Now, have you thought about how it's going to work? Regular people are going to have questions if you two suddenly show up with a kid one day."

Stiles explains the plan they'd made before he got the potion from Deaton, in which people will just think he got fat for a while and then, once the baby comes, that they used a surrogate.

"And what about the, uh…the birth itself?" the sheriff asks hesitantly, like he doesn't really want to hear the answer.

"That'll be where Deaton and Scott's mom come in. We've gotta tell them soon too, and figure out a way to do checkups and stuff so that we know the pregnancy is going well."

"You've really got it all planned out, huh?"

"Well, yeah. Having a kid's not exactly something you do lightly."

"True. Your mother and I would've had more if we had the chance," the sheriff says wistfully. He notices the sombre mood his words create and shakes himself. "I'm sure you'll both be great dads."

"Thanks. You'll be a great granddad too."

"Of course I will. It stands to reason. I'm the best dad, after all."

Stiles laughs. "Yeah, you are."

"Have you thought of names yet?"

Stiles shakes his head. "Not yet, but we've got plenty of time." He turns to look at Derek. "The only thing we've decided to far is to hyphenate our kid's last name."

The sheriff looks surprised. "Really? I thought you'd go with Hale."

"Oh please, like I was gonna let the Stilinski name die with me. It's a good name, if I say so myself, so it'll be Stilinski-Hale. In fact, if I can talk Derek into it, both of us'll change our last names to that as well after we eventually get married. After _I_ propose to _him_ , remember."

Derek pinches the bridge of his nose, but the slight upturn of the corners of his lips gives him away.

Surprise is replaced by affection on the sheriff's face. "Sounds good to me."

* * *

Two months into Stiles' pregnancy, he has his second checkup. He and Derek go to the hospital, where Melissa sneaks them into the room with the ultrasound machine and instructs him to lie down and pull up the front of his T-shirt. Once he's in position and Derek has sat down on a stool next to him, Melissa squirts some cold gel on Stiles' stomach, grabs the transducer and gets to work, all of their eyes on the monitor of the machine.

Some time elapses, during which Melissa tells Stiles that everything seems to be progressing as normal. Then she gasps.

"What is it?" Stiles asks her. He grabs Derek's hand and tries to refrain from panicking.

"Sorry, nothing's wrong!" Melissa soothes, looking apologetic. "I didn't mean to scare you. I just noticed something that surprised me."

"And it's nothing bad?"

Melissa smirks. "Not unless you'd consider having twins bad."

Stiles' mouth drops open and Derek squeezes his hand hard enough to hurt, momentarily losing control of werewolf strength. "We're having twins?"

"Yup. See here?" Still holding the transducer in place, Melissa points with her other hand at the monitor, at where two tiny peanuts are side by side. "There's baby number one, and there's baby number two."

Derek brings Stiles' hand up to his mouth and presses his lips to it.

"Wow, twins," Stiles says with wonder. "That's some powerful seed you've got there, Sourwolf."

Derek glares at him before returning his attention to the monitor.

"Do you want a printout?" Melissa enquires.

"D'you even need to ask?" Stiles fires back. "Hell yeah, we do. Wait until my dad sees it. His head'll probably explode!"

* * *

Three months into being pregnant, Stiles gets out of bed first one morning and heads into the bathroom. He does his business and then approaches his and Derek's walk-in closet while Derek takes his turn in the en suite. It's a narrow room with clothes hung up on each side, his on the left and Derek's on the right. At the end is a full-length mirror that Lydia had insisted upon when the Hale house was being rebuilt many years ago. Stiles hadn't been sure about it at the time, but he likes it now. He still doesn't really care as much as the banshee about dressing well—he prefers comfort over style—but it comes in handy occasionally, like when he and Derek go out for dinner.

After selecting an outfit for the day, he puts on his chinos, does them up and turns to the mirror as he pulls his T-shirt over his head. Something about his reflection has him stopping and taking the shirt off again. He turns to his side, eyes still glued to the mirror.

"Oh my God…" he whispers.

"Stiles? What is it?" Derek asks, racing into the closet, toothpaste smeared on the corner of his mouth.

Stiles doesn't look away from his reflection. "Look," he says, putting a hand above and below his stomach. It has a small but distinctive swell to it.

"You're starting to show," Derek says, equally in awe.

"Yup. Our babies are growing," Stiles responds. He knew it was real because of the ultrasound and the pregnancy tests—Melissa even managed to swing getting a urine sample of his tested at the hospital to make 100% sure—but seeing the first physical change to his body makes it all feel more real somehow.

It's amazing.

Derek moves to stand behind him and wraps his arms around him, both hands going right over Stiles' small belly. "Those are our kids."

"Yeah…"

Derek goes silent for a minute, just rubbing over the distended skin of Stiles' stomach, and then he makes a suggestion. "We should start planning for a nursery soon."

Stiles groans and rests his head back on the alpha's shoulder, his eyes closed. "Don't tell Lydia or Erica. They'll have all sorts of ideas and want to take over."

Derek kisses Stiles' neck. "I won't."

* * *

On month eight, Stiles comes downstairs to hear what he thinks are all of his packmates in the living room. For some reason, there's fabric hung up in the wide archway between it and the foyer, so Stiles can't see inside the room right away. He walks closer, curious as to what's going on, his hand on the huge swell of his belly like always, but before he can push aside the fabric to sneak a peek, Lydia comes out of nowhere and puts her hands over his eyes.

"Lyds, what's going on?" Stiles asks her, not fighting. There'd be no point with her.

"Just keep your eyes closed, okay?" she tells him.

Stiles sighs. "Fine."

He hears rustling in front of him, and then Lydia carefully leads him forward, their gait slow. When he thinks they've entered the living room, Lydia counts down from three, and when she takes her hands away, a bunch of people shout, "Surprise!" at him all at once, startling him.

"What the fuck?!" he exclaims, whipping his head from side to side.

Like he thought, the entire Hale Pack is there, spread across all of the sofas and even on the floor. But it's not just the pack. Melissa and his dad are there too.

Stiles finds Derek in the crowd. "What's going on?"

Erica scoffs and points to the space above the fireplace. "Isn't it obvious, you dumbass?"

Following her finger, Stiles sees a gold banner has been hung up along the wall. In elegant cursive letters, it reads 'BABY SHOWER', giving him his answer.

He's touched, especially when he notices the pile of presents on the floor and the spread of food on the coffee table. "Oh. You guys didn't have to go to all this trouble…"

"Yes we did," Lydia says as if he's crazy. "Now sit down. We've got presents and games to get through!"

Stiles does as he has been told, taking a seat on one of the sofas next to Derek. The next twenty minutes consist of everyone in the pack giving the couple present after present. They're all things that they'll need when the babies arrive, for which Stiles and Derek are grateful. It'll cut down on the amount of shopping they'll need to do.

Last to give their present is Stiles' dad. He hands off a large orange gift bag. "I finally tracked these down last week."

Stiles removes the tissue paper from the top of the bag and is delighted when he finds a whole bunch of onesies and toddler clothes that he instantly knows used to be his. There are some that are obviously made for boys, either because they're made of blue fabric or because they have soccer balls and race cars on them, but a lot of them could be used for girls too. Since both he and Derek had elected not to learn the sex of their babies until they hold them in their arms, he figures that the hand-me-downs will be useable whatever their kids end up being.

"I hope you like them," his dad says. "They've been doing no good collecting dust in my attic all these years, so…"

"They're perfect," Stiles tells him. "Thanks, dad."

* * *

After the ninth and final month has passed, Stiles is expecting the babies any day now. Deaton told him that he'd feel something when it was time, and as he stands in the kitchen and makes himself a peanut butter and jelly sandwich, he thinks he feels that something. It's a sharp pain in his lower gut, and both babies kick him with a sense of urgency that can't be denied.

"Derek!" he yells. "I think the babies are coming!"

Footsteps thunder down the stairs, and then Derek appears in the kitchen with his henley half on. "I'll call Deaton, Melissa and your dad," he says, tugging his shirt the rest of the way down his torso. "Go sit on the stairs and stay calm, okay?"

"Okay."

After a minute, Stiles is up again and out of the house as Derek leads him to the Camaro. The alpha has a duffel bag in one hand, the other on the small of Stiles' back, and he has his phone held between his ear and his shoulder. "Yeah. Yeah, okay. We'll meet you there." Derek hangs up, helps Stiles to get into the passenger seat and buckle himself up, and then he crouches down next to the open passenger door. "Deaton's cancelled his appointments for the day and closed the clinic for us. Melissa and your dad'll meet us there. Are you in any pain?"

Stiles nods. "Not constantly, but every now and then there's a twinge."

"Deaton said that's totally normal." Derek leans forward to give Stiles a chaste kiss. "Let's get going, yeah? You ready to meet our kids?"

Stiles grins. "Hell yeah."

After a fast but careful drive, Derek pulls to a stop in the parking lot of the clinic, outside of which the sheriff already waits. Derek helps Stiles out of the car again just as Melissa arrives too. She has her own bag of medical supplies, and as a group, Stiles, Derek, the sheriff and Melissa enter the clinic and make their way into the examination room in the back, where Deaton is waiting for them with the middle of the examination table covered by several big pillows and fluffy blankets.

"Well this is something," Stiles comments.

"It was short notice, but it should work," Deaton says. "Now, let's get those babies out, shall we?"

With Derek's help, Stiles strips off his loose T-shirt and gets into place on the table, his back supported by a mountain of pillows. Derek stands on one side of him and his dad is on the other, each holding onto one of his hands.

"Now, there are two options here," Deaton says, putting on rubber gloves as Melissa brings over a cart with all the supplies they'll need to deliver. "We can either give you something to help with the pain, or Derek can take care of that for you. It's your choice."

"I'll do it," Derek replies immediately.

"Okay then. Are we all ready?"

After a chorus of yeses from all five of the others in the room, it begins.

Stiles averts his eyes and focuses on Derek's face as Deaton picks up the scalpel. Just before the incision happens, he feels Derek start to drain his pain, black veins crawling up his muscular forearm. It's not quite like Stiles has been numbed, but it's close enough. He doesn't feel any pain from what Deaton's doing with Melissa's help, just a dull throbbing instead that's uncomfortable but not too much to deal with. Derek talks to him while it happens, whispering how proud he is of him and how thankful he is that Stiles is giving this to him.

Before Stiles knows it, it's done, and he hears two different cries. It's awful to have to wait for Deaton to stitch him up first, but once he has, Melissa and his dad come over and hand off the newborns to him and Derek.

"Congratulations," Melissa says, her cheeks wet and her curly hair a mess. "Two healthy baby girls."

Stiles peers down at his daughter bundled up in a small blanket, her tiny face scrunched up as she cries her distress. "Hey there," he coos, stroking a finger gently down the side of her face. She cries a couple more times, gurgles and then goes quiet, already tuckered out.

"They're beautiful," Melissa says, standing off to the side with tears still running down her face.

The sheriff agrees. "You did good, son. Have you thought of names since the last time I asked?"

Stiles shares a meaningful look with Derek, silently communicating with each other. Once he has received the response he was looking for, he nods. "Yeah, we have."

"What are they?"

Stiles makes the official introductions. "If they were both girls, we decided we were gonna name them after our moms. So, dad, I want you to meet your granddaughters, Talia and Claudia Stilinski-Hale."

There's not a dry eye in the place as the sheriff takes his turn at holding each of his grandkids, and then he, Melissa and Deaton leave the room to give the new parents some privacy.

"You look kinda hot holding our daughter, Sourwolf," Stiles says tiredly, watching as Derek gently rocks Claudia.

The werewolf shakes his head fondly, not looking away from her. "No sex until you're fully healed."

"Ruin my fun, why don't you?"

"I'm sure we'll be kept plenty busy taking care of these two."

Stiles looks down to where Talia is cradled in the crook of his left elbow. Her chubby hand is wrapped around his right index finger as she sleeps. "Very true."

Hooking his foot around a metal stool, Derek drags it close and sits next to Stiles. He leans in close and nuzzles Stiles' temple. "I love you," he murmurs.

"I love you too, Sourwolf."

**Notes for the Chapter:**

> And here's the final part. It's not my best because I wrote it quickly, but I hope it was still enjoyable. Next up, I'll be writing the third part of [_Off Limits_](https://archiveofourown.org/works/17363456/chapters/40856519), in which daddy Derek takes Stiles on their first date.
> 
> **P.S. Don't forget to subscribe to me to be notified when my future fics go live, which will all be Sterek. And please check out my past fics if you haven't already and are interested.**


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